This invention relates to an apparatus for detecting oils and the like.
With the increase in demand of petroleum and advances in the petrochemical industry in recent years, the quantity of liquids of petroleum and petrochemical products to be stored has increased and the tanks for storing these liquids have been made to have a large volume.
Consequently, the various effects from the outflow of a stored liquid from a storage tank caused by the operational mistake or mechanical damage of the pipe line connected to the tank are very serious, and the baneful influence of such an accident as mentioned above has already been demonstrated by the accidental discharge of a large quantity of heavy oil in the chemical industrial area off the coast of the Inland Sea of Japan.
In the event of the discharge of a liquid stored in a storage tank or the pipe line of the tank in large quantities it is necessary to detect the outflow of the liquid as soon as possible and to adopt promptly a proper countermeasure such as, for example, closing of the gates of an oil preventing barrier, reinforcing the oil preventing barrier, or establishing oil preventing dikes by using sandbags or oil fences to prevent the liquid from spreading widely over adjacent areas or flowing into a neighboring river or sea.
Accordingly, it is important to provide means for surely and quickly detecting the accidental discharge of a liquid stored in a storage tank from the tank or the pipe line of the tank, and several kinds of detecting means have already been proposed or devised, but all of the detecting apparatus now being in practical use are constructed on the basis of the principle of detecting an oil layer formed on the surface of water by the use of a float utilizing, for instance, the difference between the specific gravity of the oil and the water, or the difference in the electromagnetic properties of the oil from that of the water.
Using an oil detecting apparatus of the conventional design mentioned above, requires the existence of a water surface on which an oil layer formed, and it is impossible to use the oil detecting apparatus in a place where the water surface cannot exist.
Therefore, the use of the oil detecting apparatus of the conventional design is limited in that the selection of the place for arranging the apparatus is fixed.
Also, the conventional oil detecting apparatus has another defect or disadvantage in that a number of separate detecting apparatus are required with proper distribution and arrangement properly distributed to detect surely and very quickly the outflow of oil from the tank or the pipe line at any location along the peripheral wall of the tank and the pipe line before the oil spreads over a large area, and it is necessary to use a large number of detecting apparatus when the tank is of a large volume and the pipe line is extensive.